Brake Assembly Layout for Consistent Power Tool Stopping
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Solution Overview
Problem
The braking force of power tools like grinders decreases over time due to wear of brake shoes, leading to a delay in the stop time of the tip tool.
Innovation Solution
A power tool design featuring a brake assembly with a swingable brake arm and torsion springs positioned decentered from the brake member, ensuring consistent braking force by adjusting the angle and position of the brake shoes to maintain effective contact with the brake drum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brake shoes are pressed against the brake plate using coil springs, then the braking force is sufficient initially, but the braking force decreases over time due to wear of the brake shoes
Solution Approach 1:
The brake arm is designed to swing between a first position (when brake shoes are new) and a second position (when brake shoes wear), dynamically adjusting the contact position on the brake plate to maintain consistent braking force throughout the service life of the brake shoes
Solution Approach 2:
The system changes the positional parameter of the brake shoe contact point on the brake plate by swinging the brake arm, transitioning from contacting the brake plate at a first radial position to a second radial position as the brake shoes wear
2Device complexity
If the brake shoes are positioned to contact the brake plate at a fixed position, then the structure is simple, but the stop time increases as the brake shoes wear
Solution Approach 1:
The brake arm swings between two positions depending on the wear state of the brake shoes, automatically adapting to maintain optimal braking performance without requiring complex control systems or multiple components
3Force
If the brake shoes contact the brake plate at the initial position, then the braking force is strong, but the braking effectiveness deteriorates as the brake shoes wear down
Solution Approach 1:
The brake arm dynamically adjusts its position based on brake shoe wear, swinging from a first position that provides strong initial braking to a second position that maintains braking effectiveness as the brake shoes wear down
Solution Approach 2:
The brake assembly automatically compensates for brake shoe wear through the swinging motion of the brake arm, maintaining consistent braking performance without requiring external adjustment or intervention
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design maintains a consistent braking force and prevents delays in stopping the tip tool as the brake shoes wear, ensuring efficient operation over time.
Implementation Method 1
a spring having a center at a second decentered position opposite to the pivot with the center of the brake member between the center and the pivot, the spring having a movable end being elastic and in contact with an end of the swing member, the spring being configured to urge the swing member to a position at which the press member is in contact with the brake member
Data Source
AI summary
A power tool includes a brake assembly including a swing member swingable about a pivot at an axial center decentered from a center of a brake member, a press member held by the swing member to come in contact with the brake member in response to the swing member swinging, and a spring having an axial center at a second decentered position opposite to the pivot with the center of the brake member between the axial center and the pivot. The axial center is on a second line orthogonal to a first line extending through the center of the brake member and the pivot. The spring has an elastic movable end in contact with an end of the swing member to urge the swing member to a position at which the press member is in contact with the brake member with a switch being in an off state.